823 resultados para Internet and VPN.
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In recent years, due to the rapid convergence of multimedia services, Internet and wireless communications, there has been a growing trend of heterogeneity (in terms of channel bandwidths, mobility levels of terminals, end-user quality-of-service (QoS) requirements) for emerging integrated wired/wireless networks. Moreover, in nowadays systems, a multitude of users coexists within the same network, each of them with his own QoS requirement and bandwidth availability. In this framework, embedded source coding allowing partial decoding at various resolution is an appealing technique for multimedia transmissions. This dissertation includes my PhD research, mainly devoted to the study of embedded multimedia bitstreams in heterogenous networks, developed at the University of Bologna, advised by Prof. O. Andrisano and Prof. A. Conti, and at the University of California, San Diego (UCSD), where I spent eighteen months as a visiting scholar, advised by Prof. L. B. Milstein and Prof. P. C. Cosman. In order to improve the multimedia transmission quality over wireless channels, joint source and channel coding optimization is investigated in a 2D time-frequency resource block for an OFDM system. We show that knowing the order of diversity in time and/or frequency domain can assist image (video) coding in selecting optimal channel code rates (source and channel code rates). Then, adaptive modulation techniques, aimed at maximizing the spectral efficiency, are investigated as another possible solution for improving multimedia transmissions. For both slow and fast adaptive modulations, the effects of imperfect channel estimation errors are evaluated, showing that the fast technique, optimal in ideal systems, might be outperformed by the slow adaptive modulation, when a real test case is considered. Finally, the effects of co-channel interference and approximated bit error probability (BEP) are evaluated in adaptive modulation techniques, providing new decision regions concepts, and showing how the widely used BEP approximations lead to a substantial loss in the overall performance.
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La tesi ha ad oggetto lo studio e l’approfondimento delle forme di promozione commerciale presenti in Rete caratterizzate, più che da una normale evoluzione, da continue metamorfosi che ridefiniscono ogni giorno il concetto di pubblicità. L’intento è quello di analizzare il quadro giuridico applicabile alla pubblicità via Web, a fronte della varità di forme e di modalità che essa può assumere. Nel lavoro vengono passate in rassegna le caratteristiche che differenziano la pubblicità commerciale on-line rispetto a quella tradizionale; tra le quali, particolare rilievo assume la capacità d’istaurare una relazione – diretta e non mediata – tra impresa e consumatore. Nel prosieguo viene affrontato il problema dell’individuazione, stante il carattere a-territoriale della Rete, della legge applicabile al web advertising, per poi passare ad una ricognizione delle norme europee ed italiane in materia, senza trascurare quelle emanate in sede di autodisciplina. Ampio spazio è dedicato, infine, all’esame delle diverse e più recenti tecniche di promozione pubblicitaria, di cui sono messi in evidenza gli aspetti tecnico-informatici, imprescindibili ai fini di una corretta valutazione del tema giuridico. In particolare, vengono approfonditi il servizio di posizionamento a pagamento offerto dai principali motori di ricerca (keywords advertising) e gli strumenti di tracciamento dei “comportamenti” on-line degli utenti, che consentono la realizzazione di campagne pubblicitarie mirate (on-line behavioural advertising). Il Web, infatti, non offre più soltanto la possibilità di superare barriere spaziali, linguistiche o temporali e di ampliare la propria sfera di notorietà, ma anche di raggiungere l’utente “interessato” e, pertanto, potenziale acquirente. Di queste nuove realtà pubblicitarie vengono vagliati gli aspetti più critici ed esaminata la disciplina giuridica eventualmente applicabile anche alla luce delle principali decisioni giurisprudenziali nazionali ed europee in materia, nonché delle esperienze giuridiche nord-americane e di tipo autoregolamentare.
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Der Ökotourismus hat sich in den letzten Jahren zu einer Tourismussparte entwickelt, die nicht nur immer mehr Interessenten unter den Nutzern findet, sondern auch vielfältige Forschungsmöglichkeiten eröffnet.rnAus interdisziplinärer Betrachtungsweise kann man sowohl in den Gebieten der Biologie, der Wirtschaft, der Geographie, aber auch der Politik forschend tätig werden. rnDa der Tourismus in den letzten Jahren eine immer größere Bedeutung gerade für Länder mit weitestgehend intakten Naturressourcen erlangt hat, stellt sich die Frage inwieweit die Wirtschaft eines Landes auf diese Einnahmequelle angewiesen ist und ob nicht die ökologischen Belange immer weiter in den Hintergrund treten.rnAus diesem Ansatz heraus erfolgte zunächst eine qualitative und quantitative Bestandsaufnahme, die ein klares Bild vom derzeitigen Zustand in der Region ermöglicht. Darüber hinaus werden im Rahmen der Untersuchungen Zukunftsperspektiven aufgezeigt. Diese sollen verdeutlichen, inwieweit man steuernd in solche dynamischen Entwicklungsprozesse eingreifen kann oder soll.rnDie Schwerpunkte dieser Arbeit liegen in dem Bereich der Befragung von Touristen und in der Ausarbeitung eines digitalen Geländemodells zur späteren Nutzung in einem aufzubauenden Nationalpark-Infozentrum. Auf der Grundlage dieser Untersuchungen wurde ein touristisches Nutzungskonzept entwickelt und auf seine ökologischen Umsetzungschancen hin untersucht. Der Aspekt des Ökotourismus wird einleitend erörtert und definiert. Anschließend werden die Potenziale der norwegischen Tourismuswirtschaft untersucht. Die Befragungsergebnisse sowohl der norwegischen Besucher als auch der ausländischen Touristen werden in verschiedenen Korrelationen näher untersucht.rnEin gesonderter Bereich der Untersuchungen gilt dem Problemfeld des Wildcampings in Norwegen. Die dramatischen Entwicklungen der letzten Jahre rufen immer mehr Aktivisten auf den Plan. Da die Deutschen die größte Besuchergruppe darstellen, wurden innerhalb der Jahre 2003 bis 2006 Einzelinterviews geführt, um einen Überblick über das Übernachtungsverhalten der Deutschen in Norwegen gewinnen zu können. In den vergangenen 10 Jahren sind die deutschen Besucherzahlen in Norwegen leicht rückläufig, während die der Niederländer kontinuierlich steigen.rnAuf diesen Ergebnissen basierend wurden problemzentrierte Interviews mit Wohnmobilreisenden, der größten Gruppe der Individualreisenden, durchgeführt. rnMehr als 600.000 Nächte pro Jahr verbrachten die deutschen Wohnmobilreisenden außerhalb der Campingplätze, was ökologische und ökonomische Auswirkungen hat und nicht mehr mit dem in Norwegen geltenden „Allemansrett“, dem Jedermannsrecht, vereinbar ist. rnGerade die Touristen, die mit dem Wohnmobil reisen, können nur schwer mit anderen Reisenden verglichen werden, da sie mit einer völlig anderen Reiseauffassung mehr oder weniger autark unterwegs sind. Dabei legen sie besonders große Distanzen zurück und haben sich zum Ziel gesetzt, möglichst viel in kurzer Zeit zu sehen und zu erleben. Für alle Touristengruppen wurde untersucht, auf welchem Weg die Informationen für die geplante Reise beschafft wurden. Der Reiseführer ist der hauptsächliche Informationslieferant und ist teilweise für das Verhalten der Urlauber mitverantwortlich. Es konnte festgestellt werden, dass das Image des Landes und die Reisemotive das Reiseverhalten und die Wahrnehmung determinieren. Eine Untersuchung der so genannten Pull- und Push-Faktoren ergab, dass die nahezu noch unberührte Natur, die raue Landschaft sowie Ruhe und Erholung die entscheidenden Pull-Faktoren für Norwegenreisende sind. Dabei überprägt das Image Norwegens als „wildes Naturland“ die Wahrnehmung für verschiedene Problembereiche, die in Norwegen, wie auch in vielen anderen Ländern Europas, durchaus vorhanden sind. rnProblemfelder, wie Landschaftsausbeutung, Wildcamping, reduziertes Konsumverhalten und damit einhergehende rückläufige Besucherzahlen, können aber durch innovative Tourismuskonzepte und neue Reiseformen abgebaut werden. Hierbei sind Medien, wie Reiseführer, Internet und Reisemagazine, in die Pflicht zu nehmen.
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This dissertation focuses on the phenomenon of amateur subtitling, known as fansubbing. Although this phenomenon began in the late ‘80s, in recent years amateur subtitling has spread worldwide, thanks to both Internet and fan communities, also known as fandoms. At first, amateur subtitling was mainly centred on the translation of Japanese cartoons, but nowadays fandoms also tend to subtitle other kinds of audiovisual products, such as American TV series. Thanks to fansubbing, which is created by fans for other fans, fandoms claim that they would prefer to have subtitled rather than dubbed versions of audiovisual products, which is the norm in Italy and Spain. The dissertation provides a linguistic analysis of the fansubbing in Spanish of the Italian TV series Romanzo Criminale. The purpose of this dissertation is to analyse fansubbing from the linguistic point of view, as well as from the point of view of the translation. Furthermore, it aims to evaluate to what extent this translation can be compared to professional subtitling. The first chapter offers an introduction to the TV series and provides an overview of the main events and characters. The second chapter deals with an analysis of the strategies that fansubbers use to translate cultural elements from Italian into Spanish. The third chapter focuses on linguistic mistakes due to calques and linguistic interference between Italian and Spanish. The fourth chapter provides an analysis of some translation errors which occurred during the decoding of the original text. The aim is to understand if this kind of mistake might jeopardize the comprehension of the original message.
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Soil erosion models and soil erosion risk maps are often used as indicators to assess potential soil erosion in order to assist policy decisions. This paper shows the scientific basis of the soil erosion risk map of Switzerland and its application in policy and practice. Linking a USLE/RUSLE-based model approach (AVErosion) founded on multiple flow algorithms and the unit contributing area concept with an extremely precise and high-resolution digital terrain model (2 m × 2 m grid) using GIS allows for a realistic assessment of the potential soil erosion risk, on single plots, i.e. uniform and comprehensive for the agricultural area of Switzerland (862,579 ha in the valley area and the lower mountain regions). The national or small-scale soil erosion prognosis has thus reached a level heretofore possible only in smaller catchment areas or single plots. Validation was carried out using soil loss data from soil erosion damage mappings in the field from long-term monitoring in different test areas. 45% of the evaluated agricultural area of Switzerland was classified as low potential erosion risk, 12% as moderate potential erosion risk, and 43% as high potential erosion risk. However, many of the areas classified as high potential erosion risk are located at the transition from valley to mountain zone, where many areas are used as permanent grassland, which drastically lowers their current erosion risk. The present soil erosion risk map serves on the one hand to identify and prioritise the high-erosion risk areas, and on the other hand to promote awareness amongst farmers and authorities. It was published on the internet and will be made available to the authorities in digital form. It is intended as a tool for simplifying and standardising enforcement of the legal framework for soil erosion prevention in Switzerland. The work therefore provides a successful example of cooperation between science, policy and practice.
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The article provides a concise overview of the rules applicable to postal communications at the international level. Particular attention is paid to the regulations of the Universal Postal Union (UPU), the General Agreement on Trade in Services (GATS) of the World Trade Organization (WTO), as well as the relationship between the two. Outlook on possible future developments accounting for the rapid technological advances, in particular the Internet, and the liberalisation of markets wraps up the analysis. This is a 2013 update that takes into consideration the changes made in the UPU acts in 2012, as well as the latest developments in the WTO's Doha Round negotiations.
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Introduction: Video‐Supported Learning is particularly effective when it comes to skills and behaviors. Video registration of patient‐physician interviews, class room instruction or practical skills allow it to learners themselves, their peers, and their tutors to assess the quality of the learner's performance, to give specific feedback, and to make suggestions for improvement. Methods: In Switzerland, four pedagogical universities and two medical faculties joined to initiate the development of a national infrastructure for Video Supported Learning. The goal was to have a system that is simple to use, has most steps automated, provides the videos over the Internet, and has a sophisticated access control. Together with SWITCH, the national IT‐Support‐Organisation for Swiss Universities, the program iVT (Individual Video Training) was developed by integrating two preexisting technologies. The first technology is SWITCHcast, a podcast system. With SWITCHcast, videos are automatically uploaded to a server as soon as the registration is over. There the videos are processed and converted to different formats. The second technology is the national Single Logon System AAI (Authentification and Authorization Infrastructure) that enables iVT to link each video with the corresponding learner. The learner starts the registration with his Single Logon. Thus, the video can unambiguously be assigned. Via his institution's Learning Management System (LMS), the learner can access his video and give access to his video to peers and tutors. Results: iVT is now used at all involved institutions. The system works flawlessly. In Bern, we use iVT for the communications skills training in the forth and sixth year. Since students meet with patient actors alone, iVT is also used to certify attendance. Students are encouraged to watch the videos of the interview and the feedback of the patient actor. The offer to discuss a video with a tutor was not used by the students. Discussion: We plan to expand the use of iVT by making peer assessment compulsory. To support this, annotation capabilities are currently added to iVT. We also want to use iVT in training of practical skills, again for self as well as for peer assessment. At present, we use iVT for quality control of patient actor's performance.
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OBJECTIVES To improve malnutrition awareness and management in our department of general internal medicine; to assess patients' nutritional risk; and to evaluate whether an online educational program leads to an increase in basic knowledge and more frequent nutritional therapies. METHODS A prospective pre-post intervention study at a university department of general internal medicine was conducted. Nutritional screening using Nutritional Risk Score 2002 (NRS 2002) was performed, and prescriptions of nutritional therapies were assessed. The intervention included an online learning program and a pocket card for all residents, who had to fill in a multiple-choice questions (MCQ) test about basic nutritional knowledge before and after the intervention. RESULTS A total of 342 patients were included in the preintervention phase, and 300 were in the postintervention phase. In the preintervention phase, 54.1% were at nutritional risk (NRS 2002 ≥3) compared with 61.7% in the postintervention phase. There was no increase in the prescription of nutritional therapies (18.7% versus 17.0%). Forty-nine and 41 residents (response rate 58% and 48%) filled in the MCQ test before and after the intervention, respectively. The mean percentage of correct answers was 55.6% and 59.43%, respectively (which was not significant). Fifty of 84 residents completed the online program. The residents who participated in the whole program scored higher on the second MCQ test (63% versus 55% correct answers, P = 0.031). CONCLUSIONS Despite a high ratio of malnourished patients, the nutritional intervention, as assessed by nutritional prescriptions, is insufficient. However, the simple educational program via Internet and usage of NRS 2002 pocket cards did not improve either malnutrition awareness or nutritional treatment. More sophisticated educational systems to fight malnutrition are necessary.
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The Internet, and specifically web 2.0 social media applications, offers an innovative method for communicating child health information to low-income parents. The main objective of this study was to use qualitative data to determine the value of using social media to reach low-income parents with child health information. A qualitative formative evaluation employing focus groups was used to determine the value of using social media for dissemination of child health information. Inclusion criteria included: (1) a parent with a child that attends a school in a designated Central Texas school district; and (2) English-speaking. The students who attend these schools are generally economically disadvantaged and are predominately Hispanic. The classic analysis strategy was used for data analysis. Focus group participants (n=19) were female (95%); White (53%), Hispanic (42%) or African American (5%); and received government assistance (63%). Most had access to the Internet (74%) and were likely to have low health literacy (53%). The most preferred source of child health information was the family pediatrician or general practitioner. Many participants were familiar with social media applications and had profiles on popular social networking sites, but used them infrequently. Objections to social media sites as sources of child health information included lack of credibility and parent time. Social media has excellent potential for reaching low-income parents when used as part of a multi-channel communication campaign. Further research should focus on the most effective type and format of messages that can promote behavior change in this population, such as story-telling. ^
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Since its inception, Wikipedia has grown to a solid and stable project and turned into a mass collaboration tool that allows the sharing and distribution of knowledge. The wiki approach that basis this initiative promotes the participation and collaboration of users. In addition to visits for browsing its contents, Wikipedia also receives the contributions of users to improve them. In the past, researchers paid attention to different aspects concerning authoring and quality of contents. However, little effort has been made to study the nature of the visits that Wikipedia receives. We conduct such an study using a sample of users' requests provided by the Wikimedia Foundation in the form of Squid log lines. Our sample contains more that 14,000 million requests from users all around the world and directed to all the projects maintained by the Wikimedia Foundation, including different editions of Wikipedia. This papers describes the work made to characterize the traffic directed to Wikipedia and consisting of the requests sent by its users. Our main aim is to obtain a detailed description of its composition in terms of the percentages corresponding to the different types of requests making part of it. The benefits from our work may range from the prediction of traffic peaks to the determination of the kind of resources most often requested, which can be useful for scalability considerations.
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Desde la explosión de crecimiento de internet que comenzó en los años 90, se han ido creando y poniendo a disposición de los usuarios diversas herramientas para compartir información y servicios de diversas formas, desde el nacimiento del primer navegador hasta nuestros días, donde hay infinidad de lenguajes aplicables al ámbito web. En esta fase de crecimiento, en primer lugar, de cara a usuarios individuales, saldrían herramientas que permitirían a cada cual hacer su web personal, con sus contenidos expuestos. Más adelante se fue generando el fenómeno “comunidad”, con, por ejemplo, foros, o webs en las que había múltiples usuarios que disfrutaban de contenidos o servicios que la web ofreciese. Este crecimiento del mundo web en lo comunitario ha avanzado en muchas ramas,entre ellas, por supuesto, la educacional, surgiendo plataformas como la que es base del proyecto que a continuación se presenta, y herramienta básica y prácticamente ya imprescindible en la enseñanza universitaria: Moodle. Moodle es una herramienta diseñada para compatir recursos y diseñar actividades para el usuario potencial, complementando su aprendizaje en aula, o incluso siendo una vía autónoma de aprendizaje en sí misma. Se ha realizado un estudio sobre el estado de saludo de los contenidos que se exponen en Moodle, y se ha encontrado que una gran mayoría de los cursos que se pueden visitar tienen un gran número de carencias. Por un lado, hay pocos con material original explotado exclusivamente para el curso, y, si tienen material original, no se ha observado una especial atención por la maquetación. Por otro lado, hay muchos otros sin material original, y, en ambos casos, no se ha encontrado ningún curso que ofrezca material audiovisual exclusivo para el curso, presentando algunos en su lugar material audiovisual encontrado en la red (Youtube, etc). A la vista de estos hechos, se ha realizado un proyecto que intenta aportar soluciones ante estas carencias, y se presenta un curso procedente de diversas referencias bibliográficas, para la parte textual, y material audiovisual original e inédito que también se ha explotado específicamente para este curso. Este material ha sido por un lado vídeo, que se ha visionado, editado y subtitulado con software de libre distribución, y por otro lado, audio, que complementa un completo glosario que se ha añadido como extra al curso y cuyo planteamiento no se ha encontrado en ningún curso online de los revisados. Todo esto se ha envuelto en una maquetación cuidada que ha sido fruto del estudio de los lenguajes web html y CSS, de forma que, por un lado, el curso sea un lugar agradable en el que aprender dentro de internet, y por otro, se pudiesen realizar ciertas operaciones que sin estos conocimientos habrían sido imposibles, como la realización del glosario o la incrustación de imágenes y vídeos. A su vez, se ha tratado de dar un enfoque didáctico a toda la memoria del proyecto, de forma que pueda ser de utilidad a un usuario futuro que quisiese profundizar en los usos de Moodle, introducirse en el lenguaje web, o introducirse en el mundo de la edición de vídeo. ABSTRACT: Since the explosion of Internet growth beginning in the 90s, many tools have been created and made available for users to share information and services in various ways, from the birth of the first browser until today, where there are plenty of web programming languages. This growth stage would give individual users tools that would allow everyone to make an own personal website, with their contents exposed. Later, the "community" phenomenon appeared with, for example, forums, or websites where multiple users enjoyed the content or web services that those websites offered. Also, this growth in the web community world has progressed in many fields, including education, with the emerge of platforms such as the one that this project uses as its basis, and which is the basic and imperative tool in college education: Moodle. Moodle is a tool designed to share resources and design activities for the potential user, completing class learning, or even letting this user learn in an autonomous way. In this project a study on the current situation of the content present in Moodle courses around the net has been carried out, and it has been found that most of them lack of original material exploited exclusively for the courses, and if they have original material, there has been not observed concern on the layout where that material lies. On the other hand, there are many other with non original material, and in both cases, there has not been found any course that offers audio- visual material made specifically for the course, instead of presenting some audiovisual material found on the net (Youtube, etc). In view of these facts, the project presented here seeks to provide solutions to these shortcomings, presenting a course with original material exploited from various references, and unpublished audioevisual material which also has been exploited specifically for this course. This material is, on one hand, video, which has been viewed, edited and subtitled with free software, and on the other, audio, which complements a comprehensive glossary that has been added as an extra feature to the course and whose approach was not found in any of the online courses reviewed. All of this has been packaged in a neat layout that has been the result of the study of web languages HTML and CSS, so that first, the course was a pleasant place to learn on the internet, and second, certain operations could be performed which without this knowledge would have been impossible, as the glossary design or embedding images and videos. Furthermore, a didactic approach has been adopted to the entire project memory, so it can be useful to a future user who wanted to go deeper on the uses of Moodle, containing an intro into the web language, or in the world video editing.
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This paper describes a recommender system for sport videos, transmitted over the Internet and/or broadcast, in the context of large-scale events, which has been tested for the Olympic Games. The recommender is based on audiovisual consumption and does not depend on the number of users, running only on the client side. This avoids the concurrence, computation and privacy problems of central server approaches in scenarios with a large number of users, such as the Olympic Games. The system has been designed to take advantage of the information available in the videos, which is used along with the implicit information of the user and the modeling of his/her audiovisual content consumption. The system is thus transparent to the user, who does not need to take any specific action. Another important characteristic is that the system can produce recommendations for both live and recorded events. Testing has showed advantages compared to previous systems, as will be shown in the results.
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Las redes inalámbricas están experimentando un gran crecimiento en el campo de la instrumentación electrónica. En concreto las redes de sensores inalámbricas (WSN de Wireless Sensor Network) suponen la opción más ventajosa para su empleo en la instrumentación electrónica ya que sus principales características se acoplan perfectamente a las necesidades. Las WSN permiten la utilización de un número relativamente alto de nodos, están orientadas a sistemas de bajo consumo y funcionamiento con baterías y poseen un ancho de banda adecuado para las necesidades de la instrumentación electrónica. En este proyecto fin de carrera se ha realizado un estudio de las tecnologías inalámbricas disponibles, se han comparado y se ha elegido la tecnología ZigBeeTM por considerarse la más adecuada y la que más se ajusta a las necesidades descritas. En el desarrollo de mi vida profesional se han conectado dos campos teóricamente distantes como son la instrumentación electrónica y la ingeniería civil. En este proyecto se hace una descripción de la instrumentación que se utiliza para controlar estructuras como presas, túneles y puentes y se proponen casos prácticos en los que las redes WSN aportan valor añadido a instrumentación actual y a los sistemas de comunicaciones utilizados. Se definen tanto los sistemas de comunicaciones utilizados actualmente como una serie de sensores utilizados para medir los principales parámetros a controlar en una obra civil. Por último se ha desarrollado una aplicación de prueba de una red ZigBeeTM basada en equipos comerciales del fabricante Digi. consiste en una aplicación desarrollada en entorno web que maneja de forma remota, a través de Internet, las entradas y salidas digitales y analógicas de los nodos que forman la red. Se forma una red ZigBeeTM con un coordinador, un router y un dispositivo final. El Coordinador está integrado en un Gateway que permite acceder a la red ZigBeeTM a través de internet y conocer el estado de los nodos que forman la red. Con los comandos adecuados se puede leer el estado de las entradas y salidas analógicas y digitales y cambiar el estado de una salida digital. ABSTRACT. Wireless networks are experiencing tremendous growth in the field of electronic instrumentation. In particular wireless sensor networks represent the most advantageous for use in electronic instrumentation since its main characteristics fit perfectly to the needs. The WSN allow the use of a relatively large number of nodes, are aimed at low-power systems and battery operation and have an adequate bandwidth for the needs of electronic instrumentation. In this project has made a study of available wireless technologies have been compared and chosen ZigBeeTM technology was considered the most appropriate to the needs described. In the course of my professional life have connected two fields are theoretically distant as electronic instrumentation and civil engineering. In this project, there is a description of the instrumentation used to control structures such as dams, tunnels and bridges and proposes practical cases in which WSN networks add value to current instrumentation and communications systems used. There are defined as communications systems now being used as a set of sensors used to measure the main parameters to be controlled in a civil structure. Finally, I have developed a test application based ZigBeeTM networking equipment maker Digi trading. It consists of a Web-based application developed to manage remotely, via the Internet, the digital and analog inputs and outputs nodes forming the network. ZigBeeTM It forms a network with a coordinator, router and end device. The Coordinator is built into a gateway that allows access to the ZigBeeTM network through internet and know the status of the nodes forming the network. With the appropriate command can read the status of the digital inputs and outputs and change the state of a digital output.
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Telecommunications networks have been always expanding and thanks to it, new services have appeared. The old mechanisms for carrying packets have become obsolete due to the new service requirements, which have begun working in real time. Real time traffic requires strict service guarantees. When this traffic is sent through the network, enough resources must be given in order to avoid delays and information losses. When browsing through the Internet and requesting web pages, data must be sent from a server to the user. If during the transmission there is any packet drop, the packet is sent again. For the end user, it does not matter if the webpage loads in one or two seconds more. But if the user is maintaining a conversation with a VoIP program, such as Skype, one or two seconds of delay in the conversation may be catastrophic, and none of them can understand the other. In order to provide support for this new services, the networks have to evolve. For this purpose MPLS and QoS were developed. MPLS is a packet carrying mechanism used in high performance telecommunication networks which directs and carries data using pre-established paths. Now, packets are forwarded on the basis of labels, making this process faster than routing the packets with the IP addresses. MPLS also supports Traffic Engineering (TE). This refers to the process of selecting the best paths for data traffic in order to balance the traffic load between the different links. In a network with multiple paths, routing algorithms calculate the shortest one, and most of the times all traffic is directed through it, causing overload and packet drops, without distributing the packets in the other paths that the network offers and do not have any traffic. But this is not enough in order to provide the real time traffic the guarantees it needs. In fact, those mechanisms improve the network, but they do not make changes in how the traffic is treated. That is why Quality of Service (QoS) was developed. Quality of service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. Traffic is distributed into different classes and each of them is treated differently, according to its Service Level Agreement (SLA). Traffic with the highest priority will have the preference over lower classes, but this does not mean it will monopolize all the resources. In order to achieve this goal, a set policies are defined to control and alter how the traffic flows. Possibilities are endless, and it depends in how the network must be structured. By using those mechanisms it is possible to provide the necessary guarantees to the real-time traffic, distributing it between categories inside the network and offering the best service for both real time data and non real time data. Las Redes de Telecomunicaciones siempre han estado en expansión y han propiciado la aparición de nuevos servicios. Los viejos mecanismos para transportar paquetes se han quedado obsoletos debido a las exigencias de los nuevos servicios, que han comenzado a operar en tiempo real. El tráfico en tiempo real requiere de unas estrictas garantías de servicio. Cuando este tráfico se envía a través de la red, necesita disponer de suficientes recursos para evitar retrasos y pérdidas de información. Cuando se navega por la red y se solicitan páginas web, los datos viajan desde un servidor hasta el usuario. Si durante la transmisión se pierde algún paquete, éste se vuelve a mandar de nuevo. Para el usuario final, no importa si la página tarda uno o dos segundos más en cargar. Ahora bien, si el usuario está manteniendo una conversación usando algún programa de VoIP (como por ejemplo Skype) uno o dos segundos de retardo en la conversación podrían ser catastróficos, y ninguno de los interlocutores sería capaz de entender al otro. Para poder dar soporte a estos nuevos servicios, las redes deben evolucionar. Para este propósito se han concebido MPLS y QoS MPLS es un mecanismo de transporte de paquetes que se usa en redes de telecomunicaciones de alto rendimiento que dirige y transporta los datos de acuerdo a caminos preestablecidos. Ahora los paquetes se encaminan en función de unas etiquetas, lo cual hace que sea mucho más rápido que encaminar los paquetes usando las direcciones IP. MPLS también soporta Ingeniería de Tráfico (TE). Consiste en seleccionar los mejores caminos para el tráfico de datos con el objetivo de balancear la carga entre los diferentes enlaces. En una red con múltiples caminos, los algoritmos de enrutamiento actuales calculan el camino más corto, y muchas veces el tráfico se dirige sólo por éste, saturando el canal, mientras que otras rutas se quedan completamente desocupadas. Ahora bien, esto no es suficiente para ofrecer al tráfico en tiempo real las garantías que necesita. De hecho, estos mecanismos mejoran la red, pero no realizan cambios a la hora de tratar el tráfico. Por esto es por lo que se ha desarrollado el concepto de Calidad de Servicio (QoS). La calidad de servicio es la capacidad para ofrecer diferentes prioridades a las diferentes aplicaciones, usuarios o flujos de datos, y para garantizar un cierto nivel de rendimiento en un flujo de datos. El tráfico se distribuye en diferentes clases y cada una de ellas se trata de forma diferente, de acuerdo a las especificaciones que se indiquen en su Contrato de Tráfico (SLA). EL tráfico con mayor prioridad tendrá preferencia sobre el resto, pero esto no significa que acapare la totalidad de los recursos. Para poder alcanzar estos objetivos se definen una serie de políticas para controlar y alterar el comportamiento del tráfico. Las posibilidades son inmensas dependiendo de cómo se quiera estructurar la red. Usando estos mecanismos se pueden proporcionar las garantías necesarias al tráfico en tiempo real, distribuyéndolo en categorías dentro de la red y ofreciendo el mejor servicio posible tanto a los datos en tiempo real como a los que no lo son.
Resumo:
La aparición de Internet y los sistemas informáticos supuso un antes y un después en el modo que las personas emplearían para acceder a los sistemas de información. El crecimiento exponencial seguido en los años posteriores ha llevado este hecho hasta la situación actual, donde prácticamente todos los ámbitos del día a día se encuentran reflejados en la Red. Por otro lado, a la par que la sociedad se desplazaba al ciberespacio, también comenzaban a hacerlo aquellos que buscaban obtener un rendimiento delictivo de los nuevos medios y herramientas que se ponían a su disposición. Avanzando a pasos agigantados en el desarrollo de técnicas y métodos para vulnerar unos sistemas de seguridad, aún muy inmaduros, los llamados ciberdelincuentes tomaban ventaja sobre las autoridades y su escasa preparación para abordar este nuevo problema. Poco a poco, y con el paso de los años, esta distancia ha ido reduciéndose, y pese a que aún queda mucho trabajo por hacer, y que el crecimiento de los índices de ciberdelincuencia, junto con la evolución y aparición de nuevas técnicas, sigue a un ritmo desenfrenado, los gobiernos y las empresas han tomado consciencia de la gravedad de este problema y han comenzado a poner sobre la mesa grandes esfuerzos e inversiones con el fin de mejorar sus armas de lucha y métodos de prevención para combatirla. Este Proyecto de Fin de Carrera dedica sus objetivos a la investigación y comprensión de todos estos puntos, desarrollando una visión específica de cada uno de ellos y buscando la intención final de establecer las bases suficientes que permitan abordar con la efectividad requerida el trabajo necesario para la persecución y eliminación del problema. ABSTRACT. The emergence of Internet and computer systems marked a before and after in the way that people access information systems. The continued exponential growth in the following years has taken this fact to the current situation, where virtually all areas of everyday life are reflected in the Net. On the other hand, meanwhile society moved into cyberspace, the same began to do those seeking to obtain a criminal performance of new media and tools at their disposal. Making great strides in the development of techniques and methods to undermine security systems, still very immature, so called cybercriminals took advantage over the authorities and their lack of preparation to deal with this new problem. Gradually, and over the years, this distance has been declining, and although there is still much work to do and the growth rates of cybercrime, along with the evolution and emergence of new techniques, keep increasing at a furious pace, governments and companies have become aware of the seriousness of this problem and have begun to put on the table great efforts and investments in order to upgrade their weapons to fight against this kind of crimes and prevention methods to combat it. This Thesis End of Grade Project focuses its objectives on the research and understanding of all these points, developing a specific vision of each of them and looking for the ultimate intention of establishing a sufficient basis by which to manage with the required effectiveness the type of work needed for the persecution and elimination of the problem.